Hybrid construction machine

Abstract

In a hybrid excavator, a hydraulic pump and a generator motor are connected in parallel to an output shaft of an engine and a rotation motor is driven by a battery. The generator motor assists the engine by performing a motor function. Power consumption of each of the hydraulic pump and the rotation motor is detected. The output of the hydraulic pump and the rotation motor is controlled such that the sum of the detected power consumption does not exceed maximum supply power set as the sum of power that can be supplied to the hydraulic pump and the rotation motor.

1. A hybrid construction machine comprising:
 an engine; 
 a hydraulic pump connected to an output shaft of the engine; 
 a hydraulic actuator driven by the hydraulic pump; 
 a generator motor connected to the output shaft of the engine to perform a generator function and a motor function; 
 an electric actuator; 
 operating means for operating the hydraulic actuator and the electric actuator; 
 an electric storage device which supplies and receives electric power to and from the generator motor and the electric actuator; and 
 control means for controlling outputs of the hydraulic pump and the electric actuator, wherein the control means detects power consumption of each of the hydraulic pump and the electric actuator, and controls the outputs of the hydraulic pump and the electric actuator so that the sum of the detected power consumption does not exceed a maximum supply power set as the sum of power that can be supplied to the hydraulic pump and the electric actuator, wherein the control means determines the maximum power supply by detecting a charging state of the electric storage device and an engine revolution speed, and setting the maximum supply power on the basis of actual maximum system power that can be obtained from the actual charging state of the electric storage device and the actual engine revolution speed. 
 
   
   
     2. The hybrid construction machine according to  claim 1 , wherein the control means selects, as the maximum supply power, the lower of either the actual maximum system power or the maximum power of a hydraulic construction machine of the same operating capabilities as those of the hybrid construction machine. 
   
   
     3. The hybrid construction machine according to  claim 1 , wherein
 the electric actuator is a rotation motor; and 
 the control means controls the output of the hydraulic pump so as not to exceed a value obtained by subtracting the power consumption of the rotation motor from the maximum supply power. 
 
   
   
     4. The hybrid construction machine according to  claim 1 , further comprising:
 operation amount detecting means for detecting the amount of operation of the operating means for operating the respective actuators including the electric actuator; and 
 a plurality of hydraulic actuators, 
 wherein the control means divides the maximum supply power into power to be supplied to the hydraulic pump and power to be supplied to the electric actuator according to a ratio between the sum of the amounts of operation of the operating means for the respective hydraulic actuators and the amount of operation of the operating means for the electric actuator, and, on the basis of this division, controls the output of each of the hydraulic pump and the electric actuator. 
 
   
   
     5. The hybrid construction machine according to  claim 1 , further comprising:
 operation amount detecting means for detecting the amount of operation of the operating means for operating the respective actuators including the electric actuator; and 
 a plurality of hydraulic actuators, 
 wherein the control means controls the output of each of the hydraulic pump and the electric actuator on the basis of a division ratio preset according to an operation pattern of the operating means.